There have conventionally been known underwater observation apparatuses including an external load located outside of a housing and configured to be operated by a drive power supplied from a power source. Examples of this type of underwater observation apparatus include an ocean bottom seismograph (OBS) deployed on the sea bottom for seismic observation.
If power is supplied from the power source located inside of the housing forming a body of the underwater observation apparatus to an external load located outside of the housing in the related art, a through hole is formed in a wall of the housing, and a connection cable is used to connect between the external load and the power source through a watertight connector. JP 2006-30124 A (Patent Document 1) describes an example of a release structure configured to release the observation apparatus body from a weight structure attached to the observation apparatus body.